1. Seismic Petrophysics Andy May April 14, 2014

2. Rock Physics Determine the in-situ acoustic properties of the reservoir and surrounding rocks and their fluids. Use the properties to create an ideal seismic response, both compressional and shear. How does the seismic response change with porosity, permeability, fluid content, bed thickness, mineral content, etc.? Slide - 2 Seismic Petrophysics

3. How is it done? Do a full petrophysical interpretation of the wells in the area Use the interpretation to create a velocity (Rock Physics) model Geophysicist supplies a depth tie of the wells to the seismic volume, a wavelet and sections through the wells The geologist supplies the tops and info on rock variability Slide - 3

4. How is it done? The engineers supply the production characteristics of the wells The petrophysicist uses the geophysical info to create synthetics with various rock and fluid characteristics, prompted by the engineers Together the geophysicist and the petrophysicist compare the synthetics to the seismic to help decide what can be seen and how to display it Crossplots and cross sections are made comparing seismic properties to production and geological characteristics to quantify/verify the results, determine accuracy and reliability Slide - 4

5. Goals for the velocity (Rock Physics) model Borehole and invasion correct the compressional and shear sonic logs Borehole and invasion correct the density Compute the acoustic properties and the density of the borehole and formation fluids Compute a shear log when one was not measured Fill gaps in both shear and compressional sonic

6. Mechanical Properties Construction After Wally Souder, 2001 Solid, Non-Porous Material (Matrix) Dry, Porous Material (Frame) Fluid Filled, Porous Material Fluid Only

7. Processing Steps Compute “Solid Rock” density, compressional ITT, and shear ITT using volumetric sum of petrophysical results. The “theoretical values.” Add effective porosity to the solid values using Kuster-Toksoz Add borehole and formation fluids to theoretical compressional sonic using the Gassmann equation and Sxo Iterate to best pore aspect ratios by converging the difference between theoretical sonic and measured sonic compressional values. Add formation fluids to best theoretical dry frame sonic values

8. Petrophysical Rock Models

9. Defining “Shale” on logs

10. Sonic when wet Density when wet PHIEU

11. Caliper Measured shear The effect of “bad hole”

12. Measured AIGOM Example After Frederic Gallice

13. AI Model Insitu GOM Example After Frederic Gallice

14. Slide - 14

15. Slide - 15 PSTM 120 BE Well tie Reverse Polarity 300

16. Slide - 16 CQI Stack, Reverse polarity 300

17. Further Reading Keys and Xu, Geophysics, 2002. This paper incorporates all of the discussion, criticism, and corrections to the Xu and White model that had accumulated since its introduction in 1995. The analytical model presented in this paper is very good. As Leiknes, et. al. discusses the exact Kuster and Toksoz effective medium solution in Xu and White, 1995 is flawed. This approximation is robust and of high quality. Xu and White, 1996. " Physical Model for Shear...", Geophysical Prospecting. This summarizes their theory pretty well. Note their model is a PHIE and VSH model, ignore the references to Vclay. The equations make this clear, the text is a bit sloppy. Leiknes, Pedersen, and Nordahl. "Examination and Application of the Sand-clay..." This paper discusses and summarizes all of the criticism of the Xu-White model in a fair way. These issues are dealt with in the Keys and Xu paper. Batzle and Wang, 1992, “Seismic Properties of Pore Fluids.” This paper gives the equations for oil, gas, water acoustic properties. I used these in the model.

18. Petrophysicists

19. Conclusions Petrophysical velocity modeling can improve well ties to seismic Using Rock Physics and Seismic Petrophysics, well data can be compared in detail to the seismic Sonic and density logs are often bad due to borehole and invasion effects